DEMO MANUAL DC1739B-C LTC3765/LTC3766 120W Isolated Forward Converter with Synchronous Rectification DESCRIPTION Demonstration circuit 1739B-C is a 120W isolated forward converter with synchronous rectification featuring the LTC®3765/LTC3766 chip set. This circuit was designed to demonstrate the high level of performance, efficiency, and small solution size attainable using this chip set in an active-clamp-reset forward converter power supply. It operates at 240kHz and produces a regulated 12V, 10A output from an input voltage range of 9V to 36V: suitable for telecom, industrial, and other applications. It has an eighth-brick footprint area. Synchro- PERFORMANCE SUMMARY nous rectification helps to attain efficiency exceeding 94%. Secondary-side control eliminates complex opto-coupler feedback, providing fast transient response with minimum output capacitance. For other output requirements, see the LTC3766 data sheet or contact the LTC factory. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Specifications are at TA = 25°C SYMBOL PARAMETER CONDITIONS MIN TYP VIN Input Supply Range VOUT Output Voltage IOUT Output Current Range, Continuous fSW Switching (Clock) Frequency VOUT(P-P) Output Ripple VIN = 24V, IOUT = 10A (20MHz BW) IREG Output Regulation Line and Load (9VIN to 36VIN, 0AOUT to 10AOUT) ±0.27 % POUT/PIN Efficiency (See Figure 3) VIN = 24V, IOUT = 10A 92.7 % Isolation Basic Approximate Size Component Area × Top Component Height 9 MAX 36 12.0 200LFM 0 UNITS V V 10 A 240 kHz 40 mVP–P 1500 VDC 2.3 × 0.9 × 0.47 Inches dc1739bcf 1 DEMO MANUAL DC1739B-C OPERATING PRINCIPLES The LTC3765 active clamp forward controller and gate driver is used on the primary and provides start-up, gate drive, and protection functions. Once start-up is accomplished, the LTC3766 high efficiency, secondary-side synchronous forward controller takes over, and provides the LTC3765 with timing information and bias power through a small pulse transformer. When input voltage is applied, the LTC3765 commences soft-start of the output voltage. When the secondary bias source reaches the undervoltage threshold, the LTC3766 comes alive and takes control by sending encoded PWM gate pulses to the LTC3765 through T3. These pulses also provide primary bias power efficiently over a wide input voltage range. The transition from primary to secondary control occurs at some fraction of the nominal output voltage. From then on, operation and design is simplified to that of a simple buck converter. Secondary control eliminates delays, tames large-signal overshoot, and reduces output capacitance needed to meet transient response requirements. An optional LC filter stage on the input lowers rms input current. The filter must have output impedance that is less than the converter input impedance to assure stability. This may require a damping impedance. (See Linear Technology Application Note 19 for a discussion of input filter stability.) A source with a 170mΩ or higher ESR at the filter resonant frequency (~35kHz) is one way of providing damping for the filter elements provided on the DC1739B-C. For bench testing, an electrolytic capacitor has been added at the input terminals to provide suitable damping and ripple current capability. The values selected have a filter resonant frequency that is below the converter switching frequency, thus avoiding high circulating currents in the filter. QUICK START PROCEDURE Demonstration circuit 1739B-C is easy to set up to evaluate the performance of the LTC3765/LTC3766. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: b.If efficiency measurements are desired, an ammeter capable of measuring 10ADC or a resistor shunt can be put in series with the input supply in order to measure the DC1739B-C’s input current. Note: When measuring the output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the output voltage ripple by touching the probe tip and ground ring directly across the last output capacitor as shown in Figure 1. c. A voltmeter with a capability of measuring at least 36V can be placed across the input terminals in order to get an accurate input voltage measurement. 1.Set an input power supply that is capable of 9V to 36V to 9V. Then turn off the supply. 2.Direct an airflow of 200lfm across the unit for sustained operation at full load. 3.With power off, connect the supply to the input terminals +VIN and –VIN. a. Input voltages lower than 9V can keep the converter from turning on due to the undervoltage lockout feature of the LTC3765 / LTC3766. 4.Turn on the power at the input. Note: Make sure that the input voltage never exceeds 36V. 5.Check for the proper output voltage of 12V. Turn off the power at the input. 6.Once the proper output voltages are established, connect a variable load capable of sinking 10A at 12V to the output terminals +VOUT and –VOUT. Set the current for 0A. dc1739bcf 2 DEMO MANUAL DC1739B-C QUICK START PROCEDURE a. If efficiency measurements are desired, an ammeter or a resistor shunt that is capable of handling 10ADC can be put in series with the output load in order to measure the DC1739B-C’s output current. 7.Turn on the power at the input. Note: If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 8.Once the proper output voltage is again established, adjust the load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other desired parameters. b.A voltmeter with a capability of measuring at least 12V can be placed across the output terminals in order to get an accurate output voltage measurement. Figure 1. Proper Measurement Equipment Setup 96 10 12VIN EFFICIENCY (%) 8 24VIN 92 6 PD 24VIN 90 88 86 4 PD 12VIN 2 0 2 6 8 4 OUTPUT CURRENT (A) 10 POWER DISSIPATION (W) 94 0 Figure 2. Efficiency and Power Dissipation dc1739bcf 3 DEMO MANUAL DC1739B-C QUICK START PROCEDURE Figure 3. Output Ripple at 24VIN and 10AOUT (50mV, 5A, 2µs/Div, 20MHz) Figure 4. Transient Response Waveform at 24VIN and 5A – 7.5A – 5AOUT (5A, 100mV, 100µs/Div) dc1739bcf 4 DEMO MANUAL DC1739B-C QUICK START PROCEDURE Figure 5. Thermal Map, Front Side at 24VIN and 10AOUT (TA = 25°C, 200LFM) Figure 6. Thermal Map, Back Side at 24VIN and 10AOUT (TA = 25°C, 200LFM) dc1739bcf 5 DEMO MANUAL DC1739B-C PARTS LIST ITEM QTY REFERENCE Required Circuit Components 1 1 C1 2 4 C2, C3, C4, C5 3 1 C6 4 1 C7 5 2 C8, C9 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 1 2 1 1 1 3 1 1 2 2 1 1 1 1 1 2 1 1 1 2 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 4 1 1 1 C10 C12, C27 C13 C14 C16 C17, C20, C35 C18, C33 C19 C21, C23 C22 C24 C25 C28 C29 C32 C37, C44 C36 C39 D1 D3, D5 L1 L4 Q1 Q3 Q4 Q5 Q6 R1 R4 R7, R37 R10 R11 R14 R17 R18 R19, R20, R23, R24 R22 R25 R26 PART DESCRIPTION MANUFACTURER/PART NUMBER CAP., AL., TH,100uF, 50V, ME-PX SERIES CAP., X7R, 10µF, 50V, 10%, 1210 CAP., C0G, 47pF, 200V, 5%, 1206 CAP., C0G, 15pF, 200V, 5%, 0805 CAP., POSCAP, 68µF, 16V, 20%, 7343 SUNCON, 50ME100PX MURATA, GRM32ER71H106KA12 AVX, 12062A470JAT2A AVX, 08052A150JAT2A SANYO, 16TQC68M CAP., X7R, 2.2nF, 630V, 5%, 1206 CAP., X7R, 10µF, 16V, 20%, 1206 CAP., X7R, 1.0µF, 100V, 10%, 1206 CAP., X7R, 0.1µF, 250V, 10%, 1206 CAP., C0G, 1000pF, 25V, 5%, 0402 CAP., X7R, 0.1µF, 25V, 10%, 0603 CAP., C0G, 2200pF, 50V, 5%, 0603 CAP., X7R, 12nF, 50V,10%, 0805 CAP., X7R, 1.0µF, 16V 10%, 0805 CAP., C0G, 220pF, 25V, 5%, 0603 CAP., X7R, 2200pF, 250V, 10%, 1812 CAP., COG, 0.033uF, 25V, 5%, 0805 CAP., X7R, 0.010µF, 50V, 10%, 0603 CAP., X7R, 0.033µF, 25V, 10%, 0603 CAP., C0G, 47pF, 25V, 5%, 0603 CAP., C0G, 1000pF, 25V, 5%, 0603 CAP., X7R, 1500pF, 50V,10%, 0402 CAP., X7R, 1.0uF, 50V, 10%, 0805 DIODE ULTRA FAST 1A 200V SMP DIODE SCHOTTKY 40V 0.4A SOD323 INDUCTOR, 0.56µH 20% INDUCTOR, 16µH MOSFET N-CH 60V POWERPAK-SO-8 MOSFET N-CH POWERPAK-SO-8 MOSFET N-CH 150V POWERPAK-SO-8 MOSFET, P-CH, IRF6217, SO-8 MOSFET, N-CH, SUPER SOT23 RES., CHIP, 12.4Ω, 1/4W, 1%, 1206 RES., CHIP, 15k, 1W 2512 RES., CHIP, 909Ω, 1/8W, 1%, 0805 RES., CHIP, 0.005Ω, 1W, 1%, 2512 RES., CHIP, 51.1Ω, 1/8W, 1%, 0805 RES., CHIP, 0.004Ω, 3W, 5%, 1225 RES., CHIP, 28.7k, 1/8W, 1%, 0805 RES., CHIP, 100k, 1/8W, 5%, 0805 RES., CHIP, 100Ω, 1/16W, 1%, 0402 RES., CHIP, 1.82k, 1/4W, 1%, 1206 RES., CHIP, 10k, 1/10W, 1%, 0603 RES., CHIP, 2.21k, 1/10W, 1%, 0603 MURATA, GRM31A7U2J222JW31 MURATA, GRM31CR71C106MA12 MURATA, GRM31CR72A105KA01 MURATA, GRM31CR72E104KW03 TDK, C1005C0G1E102J AVX, 06033C104KAT2A MURATA, GRM1885C1H222JA01D AVX, 08055C123KAT2A MURATA, GRM21BR71C105KA01L AVX, 06033A221JAT2A MURATA, GA343QR7GD222KW01L TDK, C2012C0G1E333J AVX, 06035C103KAT2A AVX, 06033C333KAT2A AVX, 06033A470JAT2A AVX, 06033A102JAT2A AVX, 04025C152KAT2A MURATA, GRM21BR71H105KA12 VISHAY, ES1PD-M3 / 84A DIODES INC., ZHCS400TA VISHAY, IHLP2525EZERR56M01 CHAMPS PQA2050-16-LTC INFINEON, BSC028N06NS INFINEON, BSC057N08NS3G INFINEON, BSC190N15NS3 IR, IRF6217TR FAIRCHILD, 2N7002 VISHAY, CRCW120612R4FKEA VISHAY, CRCW251215KJNEG VISHAY, CRCW0805909RFKEA PANASONIC, ERJ-M1WTF5M0U VISHAY, CRCW080551R1FKEA SUSUMU, KRL6432D-C-R004-F-T5 VISHAY, CRCW080528K7FKEA VISHAY, CRCW0805100KJNEA VISHAY, CRCW0402100RFKEA VISHAY, CRCW12061K82FKEA VISHAY, CRCW060310K0FKEA VISHAY, CRCW06032K21FKEA dc1739bcf 6 DEMO MANUAL DC1739B-C PARTS LIST ITEM QTY REFERENCE 44 1 R27 45 1 R29 46 1 R35 47 1 R36 48 1 R38, R39, R56 48 1 R40 49 1 R41 49 1 R42 50 1 R44 51 1 R46 52 1 R47 53 1 R48 54 1 R49 55 1 R50 56 1 R51 57 1 R52 58 1 R53 49 1 T1 50 1 T3 51 1 U1 52 1 U2 Additional Demo Board Circuit Components 53 0 C42, C43 54 0 C15, C30, C31, C41 55 0 C38, C40 56 1 C26 57 0 C11, C34 58 1 D2 59 0 D4 60 0 D7, D8, D9, D10 61 0 D11 62 0 L5 0 Q2 63 64 0 Q7,Q9 65 0 Q8 66 12 R8, R9, R21, R28, R30-R34, R45, R54, R59 67 1 R6 68 0 R2, R3, R12, R43, R58 69 0 R55, R57, R60 70 0 T4 Hardware For Demo Board Only 5 E1, E2, E3, E4, E5 71 72 4 J1, J2, J3, J4 73 4 MTGS AT 4 CORNERS PART DESCRIPTION RES., CHIP, 0.750Ω, 1/3W, 1%, 0805 RES., CHIP, 20.0k, 1/10W, 1%, 0603 RES., CHIP, 1.82k, 1/10W, 1%, 0603 RES., CHIP, 11.5k, 1/10W, 1%, 0603 RES., CHIP, 100Ω, 1/10W, 1%, 0603 RES., CHIP, 464k, 1/10W, 1%, 0603 RES., CHIP, 14.7k, 1/10W, 1%, 0603 RES., CHIP, 78.7k, 1/10W, 1%, 0603 RES., CHIP, 102k, 1/10W, 1%, 0603 RES., CHIP, 60.4k, 1/10W, 1%, 0603 RES., CHIP, 15.0k, 1/10W, 1%, 0603 RES., CHIP, 4.99k, 1/10W, 1%, 0603 RES., CHIP, 1.87k, 1/10W, 1%, 0603 RES., CHIP, 604Ω, 1/10W, 1%, 0603 RES., CHIP, 16.2k, 1/10W, 1%, 0603 RES., CHIP, 21.5k, 1/10W,1%, 0603 RES., CHIP, 8.25k, 1/10W, 1%, 0603 TRANSFORMER, 3T:6T TRANSFORMER, 1.25T:1T I.C. LTC3765EMSE, MSOP-16PIN I.C. LTC3766EGN28, SSOP-GN28 MANUFACTURER/PART NUMBER SUSUMU, RL1220S-R75-F VISHAY, CRCW060320K0FKEA VISHAY, CRCW06031K82FKEA VISHAY, CRCW060311K5FKEA VISHAY, CRCW0603100RFKEA VISHAY, CRCW0603464KFKEA VISHAY, CRCW060314K7FKEA VISHAY, CRCW060378K7FKEA VISHAY, CRCW0603102KFKEA VISHAY, CRCW060360K4FKEA VISHAY, CRCW060315K0FKEA VISHAY, CRCW06034K99FKEA VISHAY, CRCW06031K87FKEA VISHAY, CRCW0603604RFKEA VISHAY, CRCW060316K2FKEA VISHAY, CRCW060321K5FNEA VISHAY, CRCW06038K25FKEA CHAMPS, G45R2-0603-xx COILCRAFT, CT8281-BL LINEAR TECH., LTC3765EMSE LINEAR TECH., LTC3766EGN CAP., OPT, 0402 CAP., OPT, 0603 CAP., OPT, 0805 0Ω JUMPER 0603 CAP., OPT, 1206 DIODE 4148 SOD323 DIODE OPT 220AA DIODE OPT SOD323 DIODE OPT SOT23 INDUCTOR, OPT 1608 MOSFET OPT POWERPAK-SO-8 TRANSISTOR, NPN, OPT SOT23 TRANSISTOR, NPN/PNP, OPT SOT23-6 0Ω JUMBER 0402 OPT OPT OPT VISHAY, CRCW06030000Z0EA OPT DIODES INC., 1N4148WS OPT OPT OPT OPT OPT OPT OPT VISHAY, CRCW04020000Z0ED 0Ω JUMBER 0603 RES., OPT, 0402 RES., OPT, 0805 TRANSFORMER, OPT VISHAY, CRCW06030000Z0ED OPT OPT OPT TESTPOINT, TURRET, 0.090" PBF CONNECTOR, BANANA JACK STANDOFF, NYLON 0.5 1/2" MILL-MAX, 2501-2-00-80-00-00-07-0 Keystone, 575-4 KEYSTONE, 8833(SNAP-ON) dc1739bcf 7 DEMO MANUAL DC1739B-C SCHEMATIC DIAGRAM dc1739bcf 8 DEMO MANUAL DC1739B-C SCHEMATIC DIAGRAM-COMPLETE PCB dc1739bcf Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 9 DEMO MANUAL DC1739B-C DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer. Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation dc1739bcf 10 Linear Technology Corporation LT 0813 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013